There is great need to both minimize patient exposure and maximize visibility of diagnostic details in mammography. A prerequisite to meeting this need is to measure average glandular exposure per view and detail visibility in the resulting roentgenogram. We have reported such data obtained using our present phantom, and now plan to improve its versatility. OBJECTIVES: To develop and evaluate two breast phantoms. The first is a research unit, for comparing systems and optimizing technique. The second is a simple unit for routine quality assurance. METHODS: 1. Visibility measurements will be improved by adding a "detection yield" component, so one can estimate how well, as well as how small an object is visible. This is especially important in detection of calcifications. 2. A study will be done to validate use of ionization chamber methods for depth dose measurements, to facilitate on-site evaluations. 3. Measurements with the research phantom will be done to optimize several mammography systems. The results can provide a preliminary estimate of their present capabilities and limitations. 4. The simple quality assurance phantom can help make image evaluation relatively routine, thereby assuring better mammographic technique in clinical studies.